1. Technical Field
The present invention relates to a rack housing for a steering gear. In particular, the present invention relates to a vehicle cross member that includes a rack housing for a rack and pinion steering gear.
2. Description of the Prior Art
There are four general types of rack and pinion steering systems to which the present invention relates. Each includes a rack housing through which the steering rack extends.
First is manual rack and pinion steering. In this type of steering system, the manual drive pinion assembly is attached to one end of the rack housing, and a bearing is mounted at the other end of the rack housing. The rack bar extends through the open space between. The rack bar is supported at the one end of the rack housing by the pinion assembly. The rack bar is supported at the other end of the rack housing by the bearing.
Second is belt drive electric steer. In this type of steering system, the non-driving pinion assembly is attached to one end of the rack housing, and the electric motor belt drive with ball nut assembly is mounted at the other end of the rack housing. The rack bar extends through the open space between. The rack bar is supported at one end of the rack housing by the pinion assembly. The rack bar is supported at the other end of the rack housing by the ball nut of the belt drive assembly.
Third is pinion drive electric steer. In this type of steering system, the non-driving pinion assembly is attached to one end of the rack housing, and the electric motor second pinion drive assembly is mounted at the other end of the rack housing. The rack bar extends through the open space between. The rack bar is supported at one end of the rack housing by the non-driving pinion assembly. The rack bar is supported at the other end of the rack housing by the pinion drive assembly.
Fourth is column drive electric steer. In this type of steering system, the electric motor is mounted on the steering column and drives a shaft to rotate, which drives the pinion. The pinion assembly is attached to one end of the rack housing, and a bearing is mounted at the other end of the rack housing. The rack bar extends through the open space between. The rack bar is supported at the one end of the rack housing by the pinion assembly. The rack bar is supported at the other end of the rack housing by the bearing, similar to a manual steer system.
In all these cases, the rack housing serves the following functions:
(a) Support the parts of the steering assembly, including the pinion and the drive (if any), on the vehicle.
(b) Support the rack bar for axial sliding movement on the vehicle.
(c) Contain lubricant on the rack bar. The rack gear teeth on the rack bar are lubricated. The rack bar, including the teeth, moves about 8 inches lock to lock relative to the pinion. Thus, there is a significant portion of the rack bar that is away from the pinion assembly at any time, and that portion is lubricated. The lubricant on that portion must be contained, that is, kept on the rack bar. The rack bar is enclosed in a rack housing to do this. The rack housing is typically a tubular structure that closely encloses the cylindrical rack bar. The larger cross-section of the rack housing, the stronger the piece is, which is beneficial to providing strength for the vehicle front end. On the other hand, the design of the rack housing must also be tailored to contain lubricant, which usually entails keeping the rack housing as small in cross-section as possible compared to the diameter of the rack bar.
Typically the steering assembly is a self contained unit that includes a non-structural rack housing to perform all these functions. The steering assembly including the rack housing is mounted to a structural portion of the vehicle body to support the steering assembly on the vehicle.
U.S. Pat. No. 3,864,989 shows a front suspension assembly for a motor vehicle in which a rack and pinion housing extends across the front end of the vehicle and carries the front wheel guidance arms. The rack housing is a tubular cylindrical structure slightly larger in diameter than the rack bar that passes through it.
The present invention is an apparatus for attachment to the body of a vehicle which has a front, rear and opposite sides and which has steerable wheels. The apparatus comprises a lower part having structure for fixed attachment at each of the opposite sides of the vehicle. A first steering control arm is pivotally connected to the lower part at one side of the vehicle. A second steering control arm is pivotally connected to the lower part at an opposite side of the vehicle. An upper part is connected with the lower part. A rack and pinion steering mechanism includes a rack bar movable axially in opposite directions to effect steering movement of the steerable wheels of the vehicle. The steering mechanism includes a chamber through which the rack bar extends. The chamber is defined by surfaces of the upper and lower parts.